With the development of wireless communications technologies, more and more spectrum resources are allocated for wireless or cellular communications. In different countries, the frequencies used in a regional or wireless network may be part of the spectrum resources. When User Equipment (UE) is powered on, the UE may not know the current accessible frequencies. In addition, there may be multiple frequencies of multiple access modes in a same frequency band. Therefore, when the UE is powered on, it does not know which frequency in the band and which access mode it should use to access a network.
A common method in the prior art is: searching for each possible mode such as the Global System for Mobile Communications (GSM), Long Term Evolution (LTE), and Wideband Code Division Multiple Access (WCDMA) in each available frequency range.
During the implementation of the present invention, the inventor discovers at least the following weakness in the prior art:
A frequency must be measured repeatedly. Therefore, the measurement cycle is long. Take a 60 MHz band as an example. All GSM, LTE, and WCDMA systems may operate at the band. For GSM, 60/0.2-300 frequencies need to be measured. For LTE, 60/1.25=48 frequencies need to be measured. For WCDMA, 60/5=12 frequencies need to be measured. The measurement results of each mode need to be averaged, and thus the measurement workload is heavy. In addition, due to the existence of multiple modes, it may be necessary to synchronize the frequencies of the highest power of each mode and therefore the time required is long. For a WCDMA frequency, a UE may first check whether it can be synchronized with a GSM frequency, then check whether it can be synchronized with an LTE frequency, and then check whether it can be synchronized with a WCDMA frequency. As a result, the search process takes a long time.